Roadways, parking lots, sidewalks, and other areas are often illuminated by means of a pole light, having a source of light suspended at the top of a tall pole. Pole lights may also provide the source of light at the bottom of the pole with the light distributed by a device at the top of the pole in a broad uniform pattern to the adjacent surfaces. See U.S. Pat. No. 4,989,948.
In addition to providing general area lighting to an area, such as a roadway, there are many specific applications in which lights are used to aid in directing traffic or providing extra illumination to a portion of a roadway, such as to an entrance or exit ramp. Additional lighting is often provided at an exit or entrance ramp so that the ramp is easily seen and negotiated by the motorist. Some intersections are also well illuminated, particularly so that the turn lanes are easily identifiable. Likewise, branches or convergences in highways or other roadways, are often well lit.
In addition to lighting a roadway, traffic is often assisted by means of lane markings, raised pavement markers, and the like, designed to be illuminated by the headlights of vehicles. For example, an exit lane may be marked with raised pavement markers to guide the motorist onto the exit ramp. Reflective paint may also be used to guide the motorist in a particular direction on a roadway, or to provide information to the motorist, such as "stop ahead" or "speed 55." Such systems are used extensively, but function inadequately in inclement weather conditions, such as, snow, fog, rain, or ice.
Likewise, there are disadvantages to the use of pole lights, used to distribute light in a broad pattern. Commonly used pole lights have the disadvantage of distributing light in unwanted directions. Light pollution is a serious problem, and has been the subject of governmental regulation. For example, at a residential street corner, a corner pole light may adequately light the intersection, but also provides additional stray light to the surrounding homes or businesses. In an intersection it is often only a small portion of the intersection that must be brightly lit, (e.g., only the left turn lane), but to accomplish the illumination of the desired area the entire intersection and surrounding property is illuminated. It would be desirable to be able to illuminate only the left turn lane, or other predetermined portion of the intersection, often only for a predetermined time, e.g. when the left turn arrow is illuminated.
Also, exit or entrance ramps that are illuminated would desirably only have the ramp illuminated, rather than illuminating all of the property surrounding the ramp. Presently, about 20 acres surrounding an entrance/exit ramp is illuminated, while there is typically about an acre or less of actual roadway.
It would also be desirable to provide light in a predetermined shape or pattern, such as in the shape of an arrow, a lane delineator, or to provide information, to avoid the need for using reflective paint or markers that are often obscured by inclement weather conditions.